Centrifugal circuit-changing device for electric motors.



E. S. PILLSBURY.

CENTRIFUGAL CIRCUIT CHANGING DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED JAN.19.1912.

1,1 30,017, Patented Mar. 2, 1915.

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6 ,W W Mwr/W B. S. PILLSBURY. CENTRIFUGAL CIRCUIT CHANGING DEVICE FOR ELECTRIC MOTORS.

- APPLICATION FILED JAN.19, 1912. 1,130,017.

Patented Mar. 2, 1915.

5 SHEETSSHEET 2.

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E. S. PILLSBURY.

CENTRIFUGAL CIRCUIT CHANGING DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED JAN.19, 1912 1,1 30,017. Patented Mar. 2, 1915.

5 SHEETS SHBET 3.

y [/K/l/ I) (LY 67 7/5/11 5 E. S. PILLSBURY.

CENTRIFUGAL CIRCUIT CHANGING DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED JAN. 19, I912.

Patented Mar. 2, 1915.

E. S. PILLSBURY.

GEN'IBIFUGAL CIRCUIT CHANGING DEVICE FOR ELECTRIC MOTORS.

I APPLICATION FILED JAN.19, 1912. 1,130,017.

Patented Mar. 2, 1915.

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of the three weights.

UNITED STATES PATENT OFFICE.

EDWIN S. PILLSBUR-Y, OF ST. LOUIS, MISSOURI. ASSIGNOR T0 CENTURY ELECTRIC COMPANY, A CORPORATION OF MISSOURI.

CENTRIFUGAL CIRCUIT-CHANGING DEVICE FOR ELECTRIC MOTORS.

Application filed January 19, 1912.

To all whom it may concern Be it known that I, EDVIN S. PILLSBURY, a citizen of the United States, residing at St. Louis, in the State of Missouri, have invented certain new and useful Improve merits in Centrifugal Circuit-Changing Devices for Electric Motors, of which the following is a specification.

The principal object of my invention is to provide a new and improved centrifugal device to change the circuit connections of adynamo electric machine at a certain speed.

Another object of my invention is to provide a centrifugal circuit changing device that shall have no pivotal joints to become worn or damaged by use.

These and other objects of my invention will be made clear in the following specification and claims, taken with the accompanying drawings.

For the purpose of clearly explaining the nature of my invention I have shown two specific embodiments thereof in the accompanying drawings and I now proceed to describe and explain these.

Referring to the drawings*Figure 1 is an axial section of an electric. motor' embodying one form of my invention. Fig. 2 is a section on the line 22 of Fig. 1, looking in the direction of the arrows. Fig. 3 is an elevation of the parts ]11St beyond those shown in Fig. 2, looking in the same direc tion therewith. Fig. 41 is an elevation of the same parts shown in Fig. 3, but with the ball guide racks removed. Fig. 5 is a section on the line 55 of Fig. 4, looking in the direction of the arrows. Fig. 6 is an elevation of one of the ball guide frames. Fig. 7 is a section-of the same on the line 77 of F ig. 6, looking in the direction of the arrows. Fig. 8 is a section on the line 88 of Fig. 6, looking in the direction of the arrows. Fig. 9 is a perspective view of one Fig. 10 is an axial section of an electric motor showing my invention embodied in a somewhat different form. Fig. 11 is a section on the line 11-11 of Figs. 10 and 17, looking in the direction of the arrows. Fig. 12 is a section on the line 12-12 of Fig. 11, looking in the direction of the arrows. Fig. 13 is an elevation of one element shown in section in Fig. 10. Fig. 14 is a section on the line 14-14 of Fig. 11, looking in the direction of the Specification of Letters Patent.

mther respectively in pairs.

Patented Mar. 2, 1915.

Serial N0. 672,151.

arrows. Fig. 15 is a section on the line 15-15 of Figs. 10 and 17, looking in the direction of the arrows. Fig. 16 is, an elevation of one of the three weights. Fig. 17 is an enlarged axial section of certain parts shown on a smaller scale in Fig. 10. Fig. 18 is an end elevation of the same member shown in Fig. 16.

Referring to Figs. 1 to 9, inclusive, the motor has a cylindrical stator shell 25 supporting the laminated field iron 26. The end plates of the motor have journal bearings for the rotor shaft 27 which carries the laminated armature iron 28. Surrounding the armature shaft 27 is the sheet metal cup 2.) clamped to the armature iron 28 within the ring 30. An end plate of special struc ture 31 is provided which fits inside the edge of the cup 29. This edge of the cup 29 has an inside annular groove 32 and the spring split ring 33 fitting in this annular groove 32 holds the end plate 31 in place. The end plate 33 carries three tracks 34. Each track 34 makes an acute angle with the rotor shaft 27: this angle lying in a plane containing the axis of the shaft 27. The three tracks 34 are spaced equally around the shaft 27. The end plate 31, carrying the three tracks 34, is fixed within the cup 29. A similar plate 35, having similar tracks 36, surrounds the shaft 27 inside the cup 29, the inclined tracks 34 and 36 standing opposite one an- Between the two members 31 and 35, arranged around the shaft 27. are three weights 37, one of these being shown in perspective in Fig. 9. On each side each weight carries a ball guide rack 38, the weight 37 being channeled at 39 to receive the respective racks 38. Each rack 38 has a channel 40 therein with a slot 41 at the bottom of the channel. A screw 42 passes through this slot 41, the shoulder 43 permitting free sliding movement of the rack 38. Each rack 38 has six sockets in which are the respective balls 45. The metal of the rack 38 is punched over a little. as indicated at 46, so as to retain the halls 45 in their respective sockets.

It will readily be seen that when the weights 37 .flv out radially by centrifugal force. they will spread apart the two plates 31 and 35, forcing the plate 35 to theright, as viewed in Fig.1. Attached to the plate 35 are three rods 47 which extend parallel to the rotor shaft 27 through respective holes in the rotor laminated iron. The other ends of these rods47 are attached to the sheet metal cup 48 that is slidably mounted on the shaft 27. The commutator of this motor has a plane face extending perpendicular to the armature shaft and the commutator segments are designated 49 in Fig. i

1. The shaft 27 carries an adjustable nut 50 which forms an abutment for the helical spring 51. This spring 51 pushes the cup 48 to the left, as viewed in Fig. 1. On its outer face the cup 48 carries two circumferential bands 52 and 53 forming a channel between them in which lies a series of little short circuiting pieces 54 strung on a flexible metal tape 55. These short circuiting pieces 54 are within the metal cylindrical shell 56 and when moved to the right, as viewed in Fig. 1, it will be seen that these short cireuiting pieces 54 connect the commutator segment 49 eonductively to the ring 56.

At the outer end the cup 48 engages a ring 57 and when the cup 48 moves to the right this ring 57 acts against the lugs 58 and thereby releases the brushes 59 from engagement with the commutator segment 49. Normally, the spring 51 holds the parts in position shown in Fig. 1, that is, with the weights 37 close to the shaft 27. In this condition the commutatorsegments 49 are not short circuited and the brushes 59 rest upon the commutator; accordingly, the motor is in condition to start as a commutator motor. But when a certain speed has been attained. the centrifugal force, acting on the weights 37. causes them to move out radially from the shaft 27. This crowds the frame 35 to the right, as viewed in Fig. 1, and through the rods 47 this displacement is communicated to the cup 48 which shifts the short circuiting pieces 54 into position to connect all the commutator segments 49 to the metal shell 56. Also, the brushes 59 are by this movement released from engaging the commutator. Thereafter, the armature coils being short circuited, the motor runs as an induction motor, assuming its field to be supplied with alternating current.

\Vhen the speed decreases below a certain limit the spring 51 forces the weights 37 in toward the shaft 26, thus restoring the parts to the positions shown in Fig. 1.

It will be observed that the ball carriages 38 move with approximately half the velocity of the weights 37. These carriages simply serve to hold the balls in proper spaced relation. The ball bearings that are described make very little friction, so that the device is sensitive. At the same time it is rugged; even though the weights 37 fly out with considerable violence no harm can be done, and long continued use will not wear theapparatus out nor destroy it.

It is essential that the electrical contacts should be changed by a shifting or sliding motion, and it will be seen that this is secured by my apparatus. At the same time there are no levers or pivotal joints in the mechanism for transmitting the motion. A radial movement of the weights is transmitted into a longitudinal displacement of the contact and brush-shifting el'ements.

Referring now to Figs. 10 to 18 the general arrangement of the motor and the contact and brush-shifting mechanism at the right are the same as in Fig. 1. The rotor carries a cup 29 the same as in Fig. 1. The left-hand end of this cup is closed by aplate 61 spaced off from the edge of the cup by the collar 62 through which pass screws as shown. Three weights are provided, each built up of a face plate 63 and a back plate.

64 united by the rivets 65. The plate 63 has ball channels 66 cut in it and in these are the balls 67. These balls roll between the plate 61 and the back plate 64. The stamped shell 68 is riveted to the plates 64 and 65 and filled with type metal to increase the weight of the centrifugal weights. This shell 65 is depressed at its center 69, so as to form an inclined track, 70. Each weight has a slot 71 that engages the collar 62 as a guide. Within the cup or shell 29 is a frame 72 attached to the thrust rods 47. Tongues of this frame 72 are bent through the frame and outwardly to form inclined tracks 73. Each such inclined track 73has riveted thereto a little ball retainer 74. Between each pair of inclined tracks 70 and 73 is a sihgle ball 75. The action of this device is similar to that already described in Fig. 1. Normally, the spring 51 holds the parts in the relation shown in Fig. 10; but centrifugal force, acting on the three weights described, forces them out radially. The inclined track 70 pushes through the ball 75 on the inclined track 73 and this throws the frame 72 to the right against the pressure of the spring 51.

In both of the embodiments of my inven' tion which I have illustrated, and in other forms that may fall within the scope of my invention, I regard as essential the .roller bearings between the centrifugal weights and the adjacent ,abutments. These roller bearings are necessary not so much to reduce friction as to eliminate the uncertainty of friction. It is very important that the centrifugal device shall act at a certain definite speed. With the roller bearings the frictional resistance is very nearly constant so that for a given adjustment of the opposing spring (51 in F ig. 1) the device will act at very nearly a. definite speed of rotation.

I claim:

1. In an electric motor, a circuit changing member therefor, a rotor, a shaft therefor, two opposed frames surrounding the rotor. shaft, one fixed thereon and the other slidably mounted thereon, the latter being connected to the circuit changing member, a plurality of centrifugal Weights between said frames, one of said frames having an inclined face overhanging said weights, sliding guides mounted on the sides of the weights between the weights and the frames, and rollers insaid guides.

2. In an electric motor, a circuit changing member therefor, a rotor, a shaft therefor,

two opposed frames surrounding the rotor shaft, one fixed thereon and the other slidably'mounted thereon, the latter being connected to the circuit changing member, a plurality of centrifugal weights between said frames, one of said frames having an inclined face overhanging said Weights, radial guides adapted to constrain said Weights to move radially, and rollers between said weights and frames.

In testimony whereof, I have subscribed my name.

' EDWIN S. PILLSBURY. Witnesses:

H. W. JEARMIN, JOHN F. GREAN. 

